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Journal Articles

Series studies on inter-comparison of radiation calibration fields and calibration techniques between KAERI and JAEA

Yoshitomi, Hiroshi; Tanimura, Yoshihiko*; Tatebe, Yosuke; Tsutsumi, Masahiro; Kawasaki, Katsuya; Kowatari, Munehiko; Yoshizawa, Michio; Shimizu, Shigeru*; Kim, J.-S.*; Lee, J.-G.*; et al.

Proceedings of 4th Asian and Oceanic Congress on Radiation Protection (AOCRP-4) (CD-ROM), 4 Pages, 2015/07

Journal Articles

Practice for reducing contamination of controlled area under the influence of Fukushima nuclear accident

Yoshitomi, Hiroshi; Tatebe, Yosuke; Kawai, Keiichi; Kowatari, Munehiko

Progress in Nuclear Science and Technology (Internet), 4, p.81 - 84, 2014/04

The Facility of Radiation Standards of the Japan Atomic Energy Agency provides various radiation fields for calibration and testing. It is located about 120 km away from Fukushima Dai-ichi Nuclear Power Plant, and radioactive materials discharged by the Fukushima nuclear accident contaminated around the FRS, even inside the building including radiation controlled areas. One month after the accident, the maximum contamination level in the controlled areas was 3.8 Bq/cm$$^2$$. $$^{134}$$Cs, $$^{137}$$Cs, $$^{131}$$I, $$^{132}$$Te and $$^{132}$$I were detected by $$gamma$$ spectrometry using an HPGe detector. However, contamination in controlled areas under widely contaminated environment have not been discussed in detail. As for FRS, practices for reducing contamination in the controlled areas were necessary to avoid the influence of the contamination to the calibration works. These practices described that the following two approaches were effective: (1) decontamination of the controlled areas by wiping out with wet cloth or steam cleaners, and (2) to prevent the dust with radioactive materials from letting in the controlled areas. As a result, surface contaminates inside the controlled areas were reduced to be dozens of times lower as compared with outside.

JAEA Reports

Establishment of X-ray reference fields for performance tests of radiation measuring instruments based on international standard

Shimizu, Shigeru; Sawahata, Tadahiro*; Kajimoto, Yoichi; Shikaze, Yoshiaki; Yoshihara, Yasuaki*; Tatebe, Yosuke

JAEA-Technology 2011-008, 53 Pages, 2011/06

JAEA-Technology-2011-008.pdf:2.91MB

The International Standard, ISO 4037-1, is applied worldwide for setting the condition of X-ray reference fields to be used for the performance test of radiation measuring instruments for radiation protection. X-ray reference fields were established at the Facility of Radiation Standard in Nuclear Science Research Institute in 2003 and had been operated. Recently, we rebuilt the X-ray reference fields by replacing the X-ray tube with a new model due to the damage of the old one of the middle-hard X-ray irradiation device. We have established three series of medium-hard X-ray reference fields, Narrow, Wide and High air-kerma series with 27 radiation qualities, based on ISO 4037-1. This article described quality of the X-ray fields, X-ray spectra, conversion coefficients to the dose equivalent from Air-kerma and comparison with the quality of ISO 4037-1 in the X-ray fields of medium-hard X-ray voltages ranging from 20 kV to 300 kV. Result of experiments, these X-ray reference fields were well agreed with the condition of the international standard. As a result, these X-ray reference fields were found to be used to carry out the performance test, standard irradiation based on the international standard, and an intercomparison experiment with the reference laboratories in the world.

Journal Articles

Integral experiment on beryllium with DD neutrons for nuclear data benchmarking

Kondo, Keitaro; Ochiai, Kentaro; Tatebe, Yosuke; Yagi, Takahiro; Onishi, Seiki; Takakura, Kosuke; Sato, Satoshi; Konno, Chikara

Progress in Nuclear Science and Technology (Internet), 1, p.61 - 64, 2011/02

At the Fusion Neutronics Source (FNS) facility of JAEA we have conducted various integral experiments with DT neutrons for fusion reactor materials and have made a significant progress in the verification of their nuclear data. Recently we started a new series of integral experiments with DD neutrons at FNS in order to verify nuclear data relating to DD neutrons effectively. An integral experiment on beryllium with the DD neutron source will be presented in this conference. A beryllium pseudo-cylinder assembly of 45 cm in thickness and 63 cm in the diameter was built at the distance of 20 cm from the DD neutron source, and reaction rates of the $$^{115}$$In(n,n')$$^{rm 115m}$$In, $$^{197}$$Au(n,$$gamma$$)$$^{198}$$Au and $$^{6}$$Li(n,$$alpha$$)T reactions and a $$^{235}$$U fission rate were measured. The measured values were compared with calculations with the MCNP5 code and the latest nuclear data libraries; JENDL-3.3, ENDF/B-VII.0 and JEFF-3.1. A slight disagreement between the measurement and the calculation was found in the reaction rate of In, which is sensitive to neutrons above 0.3 MeV. We identified that the disagreement originated from the angular differential cross section data of the elastic scattering around 3 MeV and from the (n,2n) reaction cross section data near its threshold energy. The calculated reaction rates of Au, Li and $$^{235}$$U, which are sensitive to low energy neutrons, showed a large overestimation, which also appeared at the beryllium integral experiment with DT neutrons previously carried out at FNS. This problem has not been solved yet.

Journal Articles

Neutron flux measurements in ITER-TBM simulating assemblies by means of multi-foil activation method

Ochiai, Kentaro; Tatebe, Yosuke; Kondo, Keitaro; Onishi, Seiki; Sato, Satoshi; Takakura, Kosuke; Konno, Chikara

Progress in Nuclear Science and Technology (Internet), 1, p.142 - 145, 2011/02

Nuclear performances of the ITER Test Blanket Module (TBM) can be calculated with a neutron transport code and nuclear data library. Neutron flux spectra in the TBM should be measured in order to validate the calculated nuclear performances of the TBM. The multi-foil activation method (MFAM) is considered to be one of the most prospective candidates for the neutron flux spectrum measurement. We have examined to measure neutron flux spectra in TBM simulating assemblies with a DT neutron source by using MFAM. We deduced neutron flux spectra in the simulated assemblies with a Monte Carlo code MCNP4C, some nuclear data and unfolding code NEUPAC. The results indicated that the adjusted neutron flux was reasonable for fast neutrons and that measured reaction rate data of more (n,$$gamma$$) reactions were necessary for more adequate adjustment for slow neutrons.

Journal Articles

Measurement of TPR distribution in natural Li$$_{2}$$TiO$$_{3}$$/Be assembly with DT neutrons

Kondo, Keitaro; Tatebe, Yosuke; Ochiai, Kentaro; Sato, Satoshi; Takakura, Kosuke; Onishi, Seiki; Konno, Chikara

Fusion Engineering and Design, 85(7-9), p.1229 - 1233, 2010/12

 Times Cited Count:8 Percentile:49.6(Nuclear Science & Technology)

In the previous blanket neutronics experiments conducted at the FNS facility of Japan Atomic Energy Agency, the following disagreements between experiments and analyses have been pointed out: (1) In the experiment with a $$^{6}$$Li-enriched Li$$_{2}$$TiO$$_{3}$$ layer and a beryllium layer, approximately 10% overestimation was found for the tritium production rate (TPR) when a neutron reflector composed of SS316 was attached. (2) In the experiment with natural Li$$_{2}$$O pebbles sandwiched by beryllium layers, TPR was overestimated near the rear beryllium layer by up to 10%. In order to confirm the above problems clearly, a new blanket neutronics experiment using a natural Li$$_{2}$$TiO$$_{3}$$ layer and beryllium layers with DT neutrons was conducted at FNS. TPR distributions inside the Li$$_{2}$$TiO$$_{3}$$ layer were measured with Li$$_{2}$$CO$$_{3}$$ pellets with and without the source reflector. The measured TPR well agreed with the calculation within an estimated experimental error of 6% in the both experiments. The influence of the reflector was not remarkable in the present experiment. Contrary to our expectation, no remarkable difference was observed in the TPR distribution around the rear beryllium layer.

JAEA Reports

Establishment of medium-hard X-ray reference fields for performance tests of radiation measuring instruments based on national standard

Shimizu, Shigeru; Sawahata, Tadahiro; Kajimoto, Yoichi; Shikaze, Yoshiaki; Yoshihara, Yasuaki*; Tatebe, Yosuke

JAEA-Technology 2010-009, 78 Pages, 2010/06

JAEA-Technology-2010-009.pdf:3.06MB

In the Japanese Industrial Standard, JIS Z 4511 sets the condition of X-ray reference fields to be used for the performance test of radiation measuring instruments for radiation protection. We renewed a X-ray tube of the medium-hard X-ray irradiation device that was damaged in the Facility of Radiation Standards in Nuclear Science Research Institute. Therefore, we established four series of medium-hard X-ray reference fields with quality index of 0.6, 0.7, 0.8 and 0.9 based on JIS Z 4511. In this process, quality of the X-ray fields, X-ray spectra, conversion coefficients to the dose equivalents from Air-kerma were evaluated in the medium-hard X-ray fields produced with X-ray tube voltage ranging from 20kV to 300kV. As a result, medium-hard X-ray reference fields were established that can provide the dose equivalent standard with good precision and wide range of test energy points and dose rates. We clarified these detailed data.

Journal Articles

Measurement of reaction rate distribution in partial mockups for the ITER TBM with DT neutrons

Sato, Satoshi; Takakura, Kosuke; Ochiai, Kentaro; Kondo, Keitaro; Tatebe, Yosuke; Onishi, Seiki; Wada, Masayuki*; Kutsukake, Chuzo; Tanaka, Shigeru; Abe, Yuichi; et al.

Fusion Science and Technology, 56(1), p.227 - 231, 2009/07

 Times Cited Count:1 Percentile:10.23(Nuclear Science & Technology)

Previously DT neutronics experiments were performed by using partial blanket mockups for Japanese ITER test blanket module at JAEA FNS, and tritium production rates (TPR) inside blanket mockups were measured in details. The calculation with the nuclear data library FENDL-2.1 and Monte Carlo code MCNP4C agreed well with most of the measured TPRs within uncertainty of 10%. On the other hand, overestimations were found for the TPR in the experiment with a reflector and the TPR around the boundary between the rear part of the breeder layer and the beryllium layer by more than 10%. In order to confirm this concern, we measured reaction rate distribution in the partial blanket mockups with DT neutrons with two solid breeder blanket partial mockups, (Be/Li$$_{2}$$TiO$$_{3}$$/Be, SS316/Li$$_{2}$$TiO$$_{3}$$/SS316). Experiments were performed with and without a neutron source reflector. In order to measure reaction rate distributions, the activation foil method was applied using Nb and Au foils in this study. Experimental analyses were performed by MCNP4C with FENDL-2.1. Calculation results to experimental ones (C/Es) on the Au reaction rate with a reflector were larger than those without one. Detailed results are presented in this conference.

Oral presentation

Neutron spectrum measurement in assemblies simulating ITER/TBM by means of multi-foil activation method

Tatebe, Yosuke; Yoshida, Shigeo*; Ochiai, Kentaro; Sato, Satoshi; Kondo, Keitaro; Onishi, Seiki; Takakura, Kosuke; Konno, Chikara; Wada, Masayuki*

no journal, , 

no abstracts in English

Oral presentation

Integral experiments for beryllium nuclear data benchmarking with DD neutrons

Kondo, Keitaro; Ochiai, Kentaro; Takakura, Kosuke; Onishi, Seiki; Sato, Satoshi; Konno, Chikara; Tatebe, Yosuke

no journal, , 

An integral experiment with the DD neutron source of the FNS facility was began in order to verify the nuclear data related to transport calculations for DD neutrons. A characterization of the DD neutron source and an integral experiment for beryllium were presented in this conference. To evaluate the characteristics of the DD neutron source of FNS, the source term in which the energy and angular distributions of the generated neutron were described based on the reaction kinematics was built into a MCNP calculation, and the target assembly was modeled in detail. To verify this calculation, the reaction rate distributions of the $$^{115}$$In(n,n')$$^{115m}$$In and $$^{58}$$Ni(n,p)$$^{58}$$Co reactions were measured at the distance of 10 cm. Measurements and the calculation agreed well, and we confirmed that the calculation was appropriate. As for the beryllium integral experiment, a beryllium pseudo-cylinder assembly of 45 cm in thickness and 63 cm in the diameter was built at the distance of 20 cm from the DD neutron source, and the neutron spectrum, the $$^{115} $$In(n,n')$$^{115m}$$In reaction rate and the $$^{235}$$U fission rate in the assembly were measured. In the experiment, a tendency that the calculation underestimated the neutron flux above 0.5 MeV as the depth inside assembly became deep was found.

Oral presentation

Improvement of the management for sealed radioisotopes by the source administration system

Tatebe, Yosuke; Onuma, Isamu; Kawasaki, Katsuya; Kowatari, Munehiko; Sawahata, Tadahiro; Sato, Yasuo; Yoshizawa, Michio

no journal, , 

no abstracts in English

Oral presentation

Comparison of calibration factors for dosemeters at $$^{241}$$Am-Be neutron standard fields using new and old sources

Kowatari, Munehiko; Tatebe, Yosuke; Sato, Yasuo; Kawasaki, Katsuya; Yoshizawa, Michio

no journal, , 

For the contribution to the effective operation of $$^{241}$$Am-Be neutron standard fields, experimental studies on the comparison of the calibration factors for neutron dosemeters by old and new sources were made. Measured calibration factors for each dosemeter were compared by estimating their E$$_{n}$$ values. Results of the variation of calibration factor for neutron dosemeters were quite satisfactory and identical calibration factors were obtained at neutron calibration fields by new and old $$^{241}$$Am-Be source.

Oral presentation

R&D of breeding functional components in ITER-TBM, 3; Prediction accuracy of the tritium production rate in TBM-simulating mockup with neutron reflector

Kondo, Keitaro; Ochiai, Kentaro; Tatebe, Yosuke; Yagi, Takahiro*; Takakura, Kosuke; Onishi, Seiki; Sato, Satoshi; Konno, Chikara

no journal, , 

In a previous neutronics experiment with a $$^{6}$$Li-enriched Li$$_{2}$$TiO$$_{3}$$ layer and a beryllium layer simulating the ITER test blanket module conducted at the FNS facility of Japan Atomic Energy Agency, the calculated tritium production rate (TPR) was by approximately 10% larger than the measured one only when a neutron source reflector composed of SS316 was attached. In order to clarify whether the deterioration of the TPR prediction accuracy originates from the reflector or not, we have conducted the same experiment as the previous experiment again and the detailed analysis of the experiment. In the present experiment, the measured TPR distribution inside the $$^{6}$$Li-enriched Li$$_{2}$$TiO$$_{3}$$ layer well agreed with the calculated one within an estimated experimental error of 6%. We conclude that the overestimation of TPR observed in the previous experiment would be due to some experimental errors and that the TPR prediction accuracy is good even in the case with the reflector.

Oral presentation

Measurement evaluation of $$beta$$-rays tissue absorbed dose rate in $$beta$$-ray reference fields made by PTB

Shimizu, Shigeru; Nemoto, Hisashi*; Kajimoto, Yoichi; Tatebe, Yosuke; Takahashi, Hiroshi*

no journal, , 

We were researched and developed in German federal physical engineering laboratory (PTB) and established the standard field of the $$beta$$ ray tissue absorbed dose rate corresponding to Series 1 of ISO6980-1(2006) to the Facility of Radiation Standard of Japan Atomic Energy Agency (JAEA) in February, 2010. We measured $$beta$$ ray tissue absorbed dose rate of this standard field using an extrapolation ionization chamber made in PTB. By the comparison between this result and standard value of PTB, both agreed well. In this announcement, we speak these evaluation results and comparison result. In addition, we speak that the $$beta$$ ray tissue absorbed dose rate at the time of the standard field use comes under a big influence by a change of the air density of the examination environment.

Oral presentation

Radiation protection practices at the nuclear science research institute under the influence of Fukushima nuclear accident, 3; Implementation for reducing radioactive contamination in FRS

Yoshitomi, Hiroshi; Tatebe, Yosuke; Kawai, Keiichi; Kowatari, Munehiko; Nidaira, Atsushi; Fukami, Tomoyo; Sawahata, Katsunori

no journal, , 

no abstracts in English

Oral presentation

Inter-comparison on calibration of personal dosemeter in neutron fields between JAEA and KAERI

Tatebe, Yosuke; Kowatari, Munehiko; Tanimura, Yoshihiko; Kawasaki, Katsuya; Yoshizawa, Michio; Im, G. S.*; Kim, S.*; Lee, J.*; Kim, B.-H.*

no journal, , 

no abstracts in English

Oral presentation

Characteristic investigation of the $$beta$$-rays reference field made by PTB, 2; Spectrum measurement and dose evaluation for the photon to be mixed in the irradiation field

Shimizu, Shigeru; Kajimoto, Yoichi; Tatebe, Yosuke; Nemoto, Hisashi*; Takahashi, Hiroshi*

no journal, , 

As a part of the characteristic investigation of the $$beta$$-rays reference field made in PTB which we maintained to a Facility of Radiation Standard of Japan Atomic Energy Agency (JAEA), we evaluated the fluence spectrum of the photon to be mixed in the irradiation field and identified characteristic X-ray, bremsstrahlung radiation and $$gamma$$-ray from this spectrum distribution and clarified the cause of the outbreak. In addition, we evaluated the H'(0.07) dose equivalent rate of the photon from this spectrum distribution and considered the influence on beta-rays dose equivalent rate of the reference field.

Oral presentation

Influence of difference in structure of the beta calibration sources on calibration for personal dosimeters

Yoshitomi, Hiroshi; Tatebe, Yosuke; Kowatari, Munehiko; Kawai, Keiichi; Miyauchi, Hideaki; Yoshizawa, Michio

no journal, , 

no abstracts in English

Oral presentation

Development of low-dose rate photon calibration field in the range of $$mu$$Sv/h

Yoshitomi, Hiroshi; Tanimura, Yoshihiko; Tatebe, Yosuke; Kawai, Keiichi; Kowatari, Munehiko; Yoshizawa, Michio

no journal, , 

no abstracts in English

Oral presentation

An Attempt to introduction of the performance index for dose rate meter

Yoshitomi, Hiroshi; Tatebe, Yosuke; Kawai, Keiichi; Kowatari, Munehiko; Yoshizawa, Michio

no journal, , 

no abstracts in English

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